May I suggest you move the info about the CONFIGURATION OPTIONS in the end of the instructions.txt file to the instructions right above the options in the Validate.php, and weed out obvious differences like LOG_UNKNOWN_VARS versus LOG_UNKNOWN_PARAMS and ALLOW_UNKNOWN_VARS versus ALLOW_UNKNOWN_PARAMS etc? Also the info about the default settings is not correct everywhere.
Also, in the info about the LOG_UNKNOWN_PARAMS you refer to setting "this to one", where you seem to mean 'true'
Apart from that, nice mod!
Tjerk.
Edit: and maybe rename Validate.php to validate.php?